Retractable hypodermic needle assembly

Abstract: A needle-syringe assembly, operable in a normal mode and convertible to a retraction mode, comprises an elongated, generally cylindrical barrel, a plunger slidably mounted in the barrel, and a needle holder carrying a hollow needle on the distal end thereof. The barrel forms a hollow nozzle located at the distal end of the barrel. The plunger forms a coaxial cavity extending therethrough, and the plunger includes a helical slot exposing a proximal portion of the coaxial cavity. The needle holder is slidably mounted in the coaxial cavity of the plunger. During the normal mode, a distal portion of the needle holder is engaged within the nozzle by a taper lock. To switch from the normal mode to the retraction mode, the taper lock is disengaged by rotary movement of the plunger relative to the barrel. While preventing rotary movement of the needle holder relative to the barrel, continued rotary movement of the plunger causes a lateral arm of the needle holder to ascend through the helical slot so that the needle holder retracts into the coaxial cavity of the plunger and the needle is concealed.

Description: Field Of The Invention The present invention generally relates to hypodermic needles. In particular, the present invention relates to various needle assemblies which conceal the sharp point of the hypodermic needle following use and in accordance with the preamble of claim 1. Background Of The Invention A hypodermic needle has many applications in modem medicine. One application is to fit the hypodermic needle into a syringe and to then insert the needle into a person's body for intra-muscular, subcutaneous, or intravenous injection of medications. Another application of the hypodermic needle is to introduce a guidewire into a central vein of a person. The hypodermic needle acts as a sharp introducing instrument through which the guidewire is advanced into the vein of the patient. Following insertion of the guidewire, the needle is removed and a catheter is threaded over the guidewire and, when in place, used for diagnostic monitoring or for therapeutic procedures such as hemodialysis. Yet another application is to collect blood samples for tests using a hypodermic needle with two sharp puncturing beveled ends mounted on the barrel of a syringe. The distal puncturing end of the needle is inserted into a person's vein while an inverted rubber-capped vacuum tube is pushed into the barrel so that the other end of the needle pierces the rubber cap of the vacuum tube. Thus, a blood sample passes from the vein, through the needle, and into the vacuum tube. A fourth application of the hypodermic needle is to coaxially mount a catheter over a hypodermic needle and to puncture a vein of a person's body with the needle. Following needle puncture, the over-the-needle ("OTN") catheter is advanced into the vein, the needle is removed, and the catheter is connected to an intravenous line for fluid infusions into the vein. The foregoing applications constitute the most common applications of hypodermic needles. A hypodermic needle entering into a patient's body is invariably contaminated by the patient's blood and body fluids. Following use of the needle, the needle presents a risk to physicians, nurses, and other health care personnel because the needle might transmit an infection or disease to such personnel if it were to accidently puncture them. Thus, health care personnel are in constant danger of contracting infections and diseases, some of which may be deadly. Other potential victims of accidental needle punctures include sanitation workers which later dispose of garbage containing the hypodermic needle. The diseases which may be transmitted by a contaminated hypodermic needle include Immune Deficiency Virus, Hepatitis, Rabies, Kure, Encephalitis, and Arbor viruses. The outcome of contracting one of these diseases is often fatal because there are no known cures for any of these diseases. Often a needle puncture in a person's skin is so trivial that it remains unrecognized until the person becomes seriously ill. The problem of suffering accidental needle punctures is well recognized. As a result, enormous inventive effort has been devoted to concealing the sharp needle point of hypodermic needles. Despite this effort, the prevalence and magnitude of needle prick-transmitted diseases is still high, as reflected in such recent articles as "Health Care" by Helene Cooper, Wall Street Journal (Nov. 25, 1992); The G.M.P. Letter (May 1992); Devices & Diagnostics Letter, Vol. 19, No. 19 (May 8, 1992); and FDA medical Bulletin, Vol. 22, No. 2 (Sept. 22, 1992). In order to avoid the transmittal of disease by needle punctures, efforts have been directed to preventing exposure of the sharp point of the hypodermic needle. One approach is to cap the needle following use. This approach, however, presents a risk of danger because it involves placing the fingers directly opposite to the needle point. To help keep the lingers away from the needle point while capping the needle, needle caps provided with wide mouths or long handles have been developed by others. While the foregoing needle caps reduce the risk of suffering a needle prick, this approach still requires a person to place his/her fingers near the needle and such finger placement is an active invitation to a needle prick. It cannot be over emphasized that even a single contaminated needle prick is unacceptable. Another approach to concealing hypodermic needles following use is to provide safe disposal containers. Such safety containers, however, do not solve the problem because needle price can and do occur even before the hypodermic needles reach their final disposal destination in the safety containers. Description of Related Art Other inventors have envisioned that the hypodermic needle of the syringe should be locked in and shielded by the syringe barrel itself. In such syringes, the needle is typically feed in an insert which is slidable in the nozzle mounted on the distal end of the syringe barrel. The insert as well as the distal end of the plunger is equipped with some type of mechanical coupling or actuator. Following injection of medicine with the advancing plunger, the insert is coupled to the distal end of the plunger so that retraction of the plunger causes retraction of the needle inside the syringe barrel. Locking is complete when a portion of the plunger is engaged to the margin of the barrel and broken off. Mechanical couplings such as that described above are disclosed in United States Patent Nos. 4,710,170; 4,790,822; 4,935,015; 4,944,723; 4,950,241; 4,986,813; 5,026,354; 5,061,249; 5,066,281; 5,098,402; 5,112,315; 5,114,404; 5,122,118; 5,171,300; 5,176,640; and 5,188,613. Similar results are achieved using spring-loaded mechanisms, as described in United States Patent Nos. 4,767,413; 4,973,316; and 5,046,508. Furthermore, U.S. Patent No. 5,125,898 to Kaufhold Jr. et al. discloses a vacuumed plunger that retracts the needle into a piston cavity. Also, U.S. Patent No. 5,045,062 to Henson discloses a fluid turbine propelled by the syringe flow to interlock the plunger and barrel. U.S. Patent No. 5,190,526 discloses a needle carriage assembly detachably fastened to the inside of the nozzle of the barrel by four catches while the plunger is provided with a coaxial cavity containing a spring-loaded mating member corresponding to a mating member extending from the needle carriage. At the end of the advancement of the plunger the mating mechanism is actuated and the needle carriage is pulled inside the cavity of the plunger. Various drawbacks are associated with the above approach. One drawback is that normal reciprocal movement of the plunger to withdraw blood and inject medicines is itself used to actuate coupling of the needle and the plunger and to cause retraction of the needle. That is, the normal functional action of moving the plunger coincides with the coupling, retracting, and locking action of the needle. This makes these syringes unreliable and decreases their functionality. Moreover, the mechanics of these syringes are complex and the results are unpredictable. Since many of these syringes require the plunger to be pulled outward in order to lodge the needle in the barrel of the syringe, such syringes tend to be bulky following use because of their increased size with the plunger pulled outward. This, in turn, adds volume to disposed syringes. An injection syringe is also known from WO-A-9015634. This syringe comprises a barrel having an annular cavity in which a ring-shaped piston is axially movable. The cavity is defined by an outer cylindrical wall and an inner cylindrical wall. The inner cylindrical wall defines an inner tube surrounding a second cavity which is separated from the annular cavity in the normal mode of the syringe. A needle holder with a needle is movably mounted in the second cavity. A handle is provided with a movable tube which is inserted into the inner tube. A retraction mechanism retracts the needle holder and the needle due to rotation of the movable tube within the inner tube. Therefore, the inner tube is provided with a threaded portion and the needle holder has projections extending through a longitudinal slot in the movable tube and into the threads of the inner tube. US-A-42 74 408 describes a syringe-type device for inserting a catheter guide wire into a blood vessel, the device having a feeder tube located in the central passage of a plunger with a ball valve at the end of the plunger. Advancement of the feeder tube displaces the ball and communicates the passage with the lumen of a needle, thereby permitting a guide wire to be fed into the vein. Alternatively, a diaphragm extends across the plunger passage to seal it. WO-A-8401510 shows in combination all features of the preamble of claim 1. Described thereon is a prefilled syringe comprising a syringe body closed at one end by a front plug and at the other end by a piston. A liquid substance is contained inside the syringe body. An injection needle is arranged substantially in the space confined by the syringe body and is suitable to be displaced prior to the injection operation by means of an actuating member up to an injection position. Accordingly, there exists a need for a hypodermic needle assembly which overcomes the above-noted drawbacks associated with existing assemblies. Summary of the Invention A primary object of the present invention is to provide a hypodermic needle assembly which is cost-effective and easy to manufacture. This objective is realized by providing a needle-syringe assembly according to claim 1. In addition, the present invention provides a guidewire insertion assembly comprising the foregoing elements of the needle-syringe assembly. The guidewire insertion assembly further includes a one-way valve disposed within the needle holder for permitting a guidewire to pass therethrough in one direction and for preventing blood from passing therethrough in the opposite direction. Also, the needle holder is hollow with openings at both the distal and proximal ends of the needle holder to permit a guidewire to pass through the needle holder. An advantage of the present invention is to provide a hypodermic needle assembly which performs all the conventional functions of the hypodermic needle, and yet allows the hypodermic needle to be retracted and concealed in a barrel or chamber of the assembly following use. Another advantage of the present invention is to provide a hypodermic needle assembly which includes a securely attached hypodermic needle and which promotes easy puncture of patient's skin and veins, and yet allows the hypodermic needle to be retracted and concealed in a barrel or chamber of the assembly in response to actuation of a retracting mechanism. Yet another advantage of the present invention is to provide a hypodermic needle assembly which avoids inadvertent activation and premature retraction of the needle before or during the use of the assembly. A related object of the present invention is to provide a hypodermic needle assembly which can be used any number of times without the needle automatically and inadvertently retracting into a barrel or chamber following a single use. Still another advantage of the present invention is to provide a hypodermic needle assembly which irretrievably locks and immobilizes a retracted needle inside the barrel or chamber such that the retracted needle cannot be removed from the barrel unless it is intentionally broken and destroyed. Thus, the assembly is irreversibly safe. Another advantage of the present invention is to provide a hypodermic needle assembly which permits the hypodermic needle to be retracted and concealed in a barrel or chamber of the assembly without the user positioning his or her fingers near the sharp point of the hypodermic needle. Yet a further advantage of the present invention is to provide a hypodermic needle assembly which is easily used by persons for legitimate self-care purposes, such as for management of diabetes, asthma, migraines, etc. Brief Description Of The Drawings Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: FIG. 1 is an exploded plan view of a needle-syringe assembly embodying the present invention; FIG. 2 is an enlarged longitudinal section of the needle-syringe assembly in FIG. 1 with the needle holder in a forward position; FIG. 3 is a fragmentary longitudinal section through a distal portion of the needle holder of the needle-syringe assembly in FIG. 1; FIG. 4 is a fragmentary longitudinal section through a proximal portion of the needle-syringe assembly in FIG. 2 with the needle holder in a retracted position; FIG. 5 is an enlarged fragmentary longitudinal section through a distal portion of the needle-syringe assembly in FIG. 2. FIG. 6a is a fragmentary perspective view of the needle-syringe assembly showing a C-clamp retaining the lateral arm of the needle holder within the oblique slot; FIG. 6b is a fragmentary perspective view of the needle-syringe assembly showing the C-clamp in a rotated position for releasing the lateral arm from the oblique slot; FIG. 7a is a fragmentary perspective view of the needle-syringe assembly showing a flag-shaped clamp retaining the lateral arm of the needle holder within the oblique slot; FIG. 7b is a fragmentary perspective view of the needle-syringe assembly showing the flag-shaped clamp in a rotated position for releasing the lateral arm from the oblique slot; FIG. 8a is a cross-section of the needle-syringe assembly showing a collar for for disengaging the lateral arm of the needle holder from the oblique slot; FIG. 8b is a fragmentary longitudinal section of the needle-syringe assembly showing the collar for disengaging the lateral arm of the needle holder from the oblique slot; FIG. 9a is a cross-section of the needle-syringe assembly showing an alternative collar for disengaging the lateral arm of the needle holder from the oblique slot; FIG. 9b is a fragmentary longitudinal section of the needle-syringe assembly showing the alternative collar for disengaging the lateral arm of the needle holder from the oblique slot; FIGS. 10 and 11 are longitudinal sections of the needle-syringe assembly in FIG. 2 showing the available range of axial movement of the plunger relative to the barrel; FIG. 12 is a longitudinal section of the needle-syringe assembly in FIG. 2 with the needle holder in the retracted position and the needle concealed by the barrel; FIG. 13 is an exploded plan view of a guidewire insertion assembly embodying the present invention; FIG. 14 is a longitudinal section of the guidewire insertion assembly in FIG. 13 with the needle holder in a forward position; FIG. 15 is a longitudinal section of the guidewire insertion assembly in FIG. 14 with the needle inserted into a vein of a patient; FIG. 16 is a longitudinal section of the guidewire insertion assembly in FIG. 14 with a guidewire inserted through the assembly into a vein of a patient; and FIG. 17 is a longitudinal section of the guidewire insertion assembly in FIG. 14 with a guidewire inserted into a vein of a patient, the needle carrier in the retracted position, and the needle concealed by the needle chamber; While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. Description Of The Preferred Embodiments Turning now to the drawings, FIGS. 1-12 illustrate a needle-syringe assembly including a barrel 100, a cylindrical plunger 102, a hollow plunger cap 104, a hypodermic needle 106, and a needle holder 108. The barrel 100 is a hollow nice with a hollow tapered conical nozzle 110 at the distal end thereof. The interior of the conical nozzle 110 communicates with the hollow tube of the barrel 100. The proximal end or the barrel 100 is provided with a transverse circular base place 112 employed to pull or push the plunger 102 in relation to the barrel 100. The barrel 100 contains an oblique retainer slot 114 and a longitudinal travel slot 116 connected thereto. The longitudinal travel slot 116 extends through the base plate 112 at the proximal end of the barrel 100. The outer surface of the barrel 100 preferably contains graduations indicating the volume level of fluid in the barrel 100. These graduations take into account the volume of the needle holder 108. In the preferred embodiment, the inner diameter at the junction 118 of the nozzle 110 and barrel 100 is 3.048 mm (0.120 inches) while the inner diameter at the distal end 120 of the nozzle 110 is 2.794 mm (0.110 inches). Moreover, the longitudinal distance between these two inner diameters is 6.35 mm (0.250 inches). The diametric difference between the two diameters forms a taper in the nozzle 110 which is conventionally known as a locking female luer taper, and the angle formed by the diametric difference is conventionally known as a locking taper angle. The elongated plunger 102 includes a head 124 to accommodate the hollow rubber plunger cap 104, and a base plate 126 grasped by a user to permit linear or rotary movement of the plunger 102 relative to the barrel 100. The surface of the base plate 126 is provided with longitudinal grooves to facilitate gripping of the base plate 126 for rotary movements of the plunger 102. The outer diameters of the ends 128, 130 of the resilient plunger cap 104 are wider than the outer diameter of the central cylindrical portion 131 of the cap 104. Furthermore, the outer diameters of the ends 128, 130 of the cap 104 are slightly larger than the inner diameter of the barrel 100 so that an air-tight and liquid-tight seal is formed between the plunger cap 104 and the inner surface of the barrel 100. The distal end 128 of the cap 104 is conical and abuts the complementary distal end of the barrel 100 when the plunger 102 is advanced inside the barrel 100. The head 124 of the plunger 102 is configured to fit tightly within the hollow plunger cap 104. With the cap 104 locked over the head 124 of the plunger 102, the flat proximal end 130 of the cap 104 abuts the flat surface 135 of the plunger 102. Due to the air-tight and liquid-tight seal between the plunger cap 104 and the barrel 100, forward axial movement of the plunger 102 inside the barrel 100 creates pressure in the barrel interior between the distal end 128 of the plunger cap 104 and the distal end of the barrel 100. Similarly, backward axial movement of the plunger, i.e., pulling out the plunger, creates a vacuum in that barrel interior. In an alternative embodiment, the resilient cap 104 is substituted with a resilient "O" ring at the flat end of the plunger 102. The hypodermic needle 106 is mounted on the distal end of the elongated cylindrical needle holder 108, which is detachably interlocked to the barrel 100 by the taper lock between the distal cylindrical portion 133 of the needle holder 108 and the inner surface of the nozzle 110. To aid in securing the distal cylindrical portion 133 of the needle holder 108 within the nozzle 110 and to create an air-tight and liquid-tight seal between the needle holder 108 and the inner surface of the nozzle 110, the mating surfaces of the nozzle 110 and the needle holder 108 are textured. The tight contact provided by the textured surfaces also functions to minimize leakage of barrel contents through the nozzle 110 while injecting fluids. To further minimize leakage, the needle holder 208 is provided with an elastomeric or rubber "O" ring 164 at the proximal end of the cylindrical portion 133. The "O" ring 164 mates with circular grave 166 formed in the inner surface of the nozzle 210. The "O" ring 164 and the groove 166 strengthen the contact between the mating surfaces of the nozzle 110 and the needle holder 108. In addition, the apex 137 of the barrel 100 may also be inverted (not shown) such that the angle of the apex 137 is sloped toward the proximal end of the barrel 100 rather than away from the proximal end of the barrel 100. With such a barrel apex, leakage of barrel contents is further minimized by providing the needle holder 108 with a mating inverted portion. Prior to using the needle-syringe assembly, the needle 106 is covered by a protective cap (not shown) which prevents needle pricks and preserves sterility prior to use. Both the needle 106 and the distal portion of the needle holder 108 are hollow, and the interior of the hollow needle 106 communicates with the interior of the hollow distal portion of the needle holder 108. The needle holder 108 further communicates with the interior of the barrel 100 by a transverse channel 132 which intersects the interior of the needle holder 108 (FIG. 3). Prior to and during use of the needle-syringe assembly for injection of medicine or withdrawal of blood (hereafter referred to as "normal use"), the transverse channel 132 is positioned at the apex 137 of the barrel 100. The transverse channel 132 permits blood or medicine to enter or exit from the barrel 100 via the needle holder 108 and the needle 106. The distal cylindrical portion 133 of the needle holder 108 is sized to fit tightly within the nozzle 110 of the barrel 100 to form the disengagable taper lock. The taper lock is formed by axially telescoping identical diameters. In particular, the cylindrical portion 133 of the needle holder 108 has outer diametric dimensions equivalent to the inner diametric dimensions of the nozzle 110. Thus, the distal end of the cylindrical portion 133 has an outer diameter of 2.794 mm (0.110 inches) while the proximal end of the cylindrical portion 133, which is positioned adjacent to the junction 118 between the nozzle 110 and the barrel 100, has an outer diameter of 3.048 mm (0.120 inches). The plunger 102 contains a coaxial cavity 134 extending from the head 124 to the base plate 126. The coaxial cavity 134 is diametrically sized to accommodate the needle holder 108 and to permit reciprocating axial relative movement between the needle holder 108 and the plunger 102. Moreover, the distal portion 128 of the plunger cap 104 contains a tight axial cavity 136 sized to accommodate the needle holder 108 and, at the same time, to prevent air or liquid leakage through the cap 104. If a resilient "O" ring is used in place of the plunger cap 104, another "O" ring is placed in the coaxial cavity 134 to surround and seal the needle holder 108. The coaxial cavity 134 is exposed to the outer surface of the plunger 102 by a longitudinal slot 138 and a helical slot 140. The longitudinal slot 138 extends from the distal end of the plunger cap 104 to the distal end of the helical slot 140. The longitudinal slot 138 leads into the helical slot 140, which extends between the proximal end of the longitudinal slot 138 to a longitudinal position spaced from the base plate 126. The functions of these two slots 138, 140 are discussed below. During normal use of the needle-syringe assembly, the distal cylindrical portion 133 of the needle holder 108 is locked within the nozzle 110 of the barrel 100, and the needle holder 108 is slidably mounted within the coaxial cavity 134 of the plunger 102 as well as the coaxial cavity 136 of the plunger cap 104 (FIGS. 2, 5, 10, and 11). The needle holder 108 is L-shaped, having a leg portion 142 and a lateral arm 144 oriented ninety degrees from the leg portion 142. With respect to the barrel 100, the leg portion 142 of the L-shaped holder 108 extends coaxially from the nozzle 110 to the oblique slot 114, and the lateral arm 144 extends transversely through the distal portion of the oblique slot 114 (via the longitudinal slot 138 in the plunger 102). The lateral arm 144 is maintained within the distal portion of the oblique slot 114 by a C-clamp 147 anchored in a groove in the outer surface of the barrel 100 (FIGS. 6a and 6b). The C-clamp 147 is snugly positioned between the base plate 112 of the barrel 100 and the lateral arm 144, biasing the lateral arm 144 into the distal portion of the oblique slot 114 during normal use of the assembly. Alternatively, a flag-shaped clamp 149 may be rotatably hinged to an L-shaped lateral arm 144a (FIGS. 7a and 7b). The flag-shaped clamp 146 is positioned between the lateral arm 144a and the base plate 112 to maintain the lateral arm 144a within the oblique slot 114, and is rotated from beneath the base plate 112 to permit movement of the lateral arm 144a out of the oblique slot 114. Reciprocating axial movement of the plunger 102 is limited by the available range of axial movement of the plunger 102 relative to the barrel 100 and the needle holder 108 (FIGS. 10-11). During normal use of the needle-syringe assembly, the lateral arm 144 of the needle holder 108 extends from the coaxial cavity 134 of the plunger 102, through the longitudinal slot 138 in the plunger 102, and through the distal portion of the oblique slot 114. The width of the longitudinal slot 138 is sized to accommodate the lateral arm 144. The length of the longitudinal slot 138 is preferably selected such that the length of the plunger cap 104 plus the length of the longitudinal slot 138 is substantially equal to the length between the apex 137 of the barrel 100 and the distal portion of the obique slot 114. During normal use of the needle-syringe assembly, the barrel 100 and needle holder 108 are held stationary and the plunger 102 is free to move relative to the barrel 100 and the needle holder 108. The needle holder 108 is engaged to the barrel 100 by virtue of the taper lock between the distal cylindrical portion 133 and the nozzle 110 and the maintenance of the lateral arm 144 in the oblique slot 114 by the clamp 147. The plunger 102 is free to move relative to the needle holder 108 because the lateral arm 144 is not locked to the plunger 102 during normal use. The plunger 102 is free to move relative to the barrel 100 as long as the lateral arm 144 is free to move longitudinally through the longitudinal slot 138. The proximal and distal ends of the longitudinal slot 138 limit the available range of reciprocating relative axial movement of the plunger 102 (FIGS. 10-11). Due to the selected length of the longitudinal slot 138, forward axial movement of the plunger 102 is further limited by contact of the distal end 128 of the plunger cap 104 with the apex 137 of the barrel 100 (FIG. 10). With the foregoing arrangement of the lateral arm 144, the plunger 102 can move only in the axial direction, rotary movement being prevented by the positioning of the lateral arm 144 in both the longitudinal slot 138 in the plunger 102 and the oblique slot 114 in the barrel 100 and by the taper lock between the needle holder 108 and the barrel nozzle 110. The clamp engagement of the lateral arm 144 in the oblique slot 114 prevents displacement of the lateral arm 144 into the helical slot 140 and further inhibits rotary movement of the plunger 102. In other words, during normal use the needle holder 108 is locked to the barrel 100 by the taper lock at the nozzle 110 and the fixed engagement of the lateral arm 144 within the oblique slot 114 by the clamp 147. At the same time, the plunger 102 is axially movable relative to the needle holder 108 because the coaxial cavity 134 and the longitudinal slot 138 permit the plunger 102 to slide over the leg and lateral arms 142, 144. As long as the lateral arm 144 of the needle holder 108 is located in the longitudinal slot 138 in the plunger 102, the needle-syringe assembly is in normal operative mode. In the retraction mode of operation following normal use of the needle-syringe assembly, the needle 106 is retracted into the plunger 102 and the barrel 100 by axially moving the needle holder 108 toward the proximal end of the plunger 102. This is accomplished by first advancing the plunger 102, if it is not already fully advanced, into the barrel 100 so that the lateral arm 144 of the needle holder 108 moves to the proximal end of the longitudinal slot 138 (FIG. 10). The lateral arm 144 is disengaged from the oblique slot 114 of the barrel 100 by rotating the clamp 147 until the gap in the C-clamp is in annular alignment with the lateral arm 144 (FIG. 6b). Next, the plunger 102 and the lateral arm 144 of the needle holder 108 are rotated counterclockwise (as viewed from the proximal end) so that the plunger 102 applies a rotary force to the needle holder 108 and the oblique slot 114 simultaneously applies a proximally-directed longitudinal force to the needle holder 108. The compound rotary and longitudinal force releases the taper lock between the barrel nozzle 110 and the needle holder 108 and forces the lateral arm 144 to move proximally through the oblique slot 114. As the lateral arm 144 is forced proximally through the oblique slot 114, the needle holder 108 begins to retract into the coaxial cavity 134 in the plunger 102. Continued rotary movement of the plunger 102 causes the lateral arm 144 to move from the oblique slot 114 to the travel slot 116 in the barrel 100 and from the longitudinal slot 138 to the helical slot 140 in the plunger 102. As the plunger 102 is still further rotated relative to the barrel 100, the lateral arm 144 moves through the remainder of the helical slot 140 in the plunger 102 without any further rotation of the needle holder 108. One rotation of the plunger 102 causes the lateral arm 144 to traverse the length of the single-revolution helical slot 140. During part of this continued rotation of the plunger 102, the lateral arm 144 moves proximally through the travel slot 116 until the lateral arm 144 reaches the proximal end of the barrel 100. The travel slot 116 prevents the lateral arm 144 from rotating relative to the barrel 100 so that the needle holder 108 does not rotate with the plunger 102. As the plunger 102 is further rotated, the lateral arm 144 exits the travel slot 116 and moves beyond the proximal end of the barrel 100. At this point, to limit rotation of the lateral arm 144 relative to the barrel 100, the assembly is provided with a flexible string 146 of elastomer or wire connecting the lateral arm 144 with the base plate 112 of the barrel 100 (FIGS. 2 and 4). Not only does the flexible string 146 limit rotation of the needle holder 108 relative to the barrel 100, but it also prevents the plunger 102 from being separated from the barrel 100 so that spillage of syringe contents does not occur. When the lateral arm 144 of the needle holder 108 reaches the proximal end of the helical slot 140, retraction of the needle holder 108 and needle 106 is complete (FIG. 12). At the proximal end of the helical slot 140, a detente 148 traps the ascending lateral arm 144 of the needle holder 108. The needle holder 108 and most of the needle 106 are now locked inside the plunger cavity 134. The plunger 102 itself is locked to the barrel 100 by the flexible string 146 and the needle holder 108, and cannot undergo either rotary or reciprocal movements. As a result, the needle-syringe assembly is rendered inoperative and is ready for disposal. As illustrated in FIG. 12, in the retracted position the needle holder 108 is completely retracted inside the coaxial cavity 134 in the plunger 102, and the needle 106 is completely retracted and concealed inside the barrel 100. To assure that the needle 106 is completely inside the barrel 100, the longitudinal distance between the distal and proximal ends of the helical slot 140 is slightly greater than the exposed length of the hypodermic needle 106 when the plunger 102 is in its fully advanced position. To operate the needle-syringe assembly, the protective cap is removed from the needle, and the required amount of medication is aspirated into the barrel 100. Next, the injection site on the body of a patient is determined and the skin is cleaned with an antiseptic solution. Following percutaneous entry of the needle into the patient, location of the needle tip in the vein is confirmed by aspirating a small amount of blood into the transparent barrel 100. The plunger 102 of the assembly is then advanced to force the medication from the barrel 100 into the vein. After the medication is administered, the needle 106 is withdrawn from the patient, the C-clamp 147 is released, and the base plate 126 of the plunger 102 is rotated counterclockwise until the lateral arm 144 of the needle holder 108 reaches the proximal end of the helical slot 140. The helical slot 140 may alternatively be configured to require clockwise, instead of counterclockwise, rotation of the plunger 102. With the needle 106 completely retracted inside the barrel 100, the needle-syringe assembly is discarded in its entirety. In an alternative embodiment, the lateral arm 144 is L-shaped and is provided with a pin 151 connected orthogonal to the end of the longitudinal portion of the lateral arm 144 (FIG. 6a). Following needle retraction, the pin 151 prevents separation of the plunger 102 from the barrel 100 by engaging the base plate 112 of the barrel 100 at the proximal end of the longitudinal slot 116. The pin 151 prevents the end portion of the lateral arm 144 containing the pin 151 from moving proximally beyond the base plate 112 of the barrel 100. In another alternative embodiment, the distal cylindrical portion 133 of the needle holder 108 is disengaged from the nozzle 110 using a collar 153 rotatably mounted on the barrel 100 (FIGS. 8a and 8b). The collar 153 includes a slot 155 with an oblique portion and a longitudinal portion which counter the respective oblique slot 114 and longitudinal slot 116 in the barrel 100 as shown in FIG. 8b. The collar 153 is retained on the barrel 100 proximal to the pins 159 protruding outwardly from the barrel 100 adjacent the distal end of the collar 153. During normal use of the needle-syringe assembly, the lateral arm 144 of the needle holder 108 extends through the distal portion of the oblique slot 114 in the barrel 100 and the distal portion of the oblique portion of the collar slot 155. To initiate needle retraction, the collar 153 is rotated clockwise (as viewed from the proximal end). While rotating the collar 153 clockwise, the edge of the oblique portion of the collar slot 155 acts as a cam surface which disengages the distal cylindrical portion 133 of the needle holder 108 from the nozzle 110 and forces the lateral arm 144 to move proximally through the oblique slot 114. The lateral arm 144 is forced proximally through the oblique slot 114 by virtue of the "scissors-type" action between the oblique slot 114 and the collar slot 155. When the lateral arm reaches the proximal end of the oblique slot 114, further needle retraction is accomplished in the manner previously described. That is, the plunger 102 is rotated to draw the lateral arm 144 through the longitudinal slot 116 in the barrel 100 while the lateral arm 144 moves proximally through the helical slot 140 in the plunger 102. As the lateral arm 144 exits the collar 153 via the longitudinal portion of the collar slot 155, the lateral arm engages a hook retaining member 157 slidably mounted in the collar 153. Continue rotation of the plunger 102 relative to the barrel 100 moves the lateral arm 144 proximally beyond the proximal end of the barrel 100. However, since the hook retaining member 157 is annularly fixed relative to the collar 153 and the collar 153 is now annularly fixed relative to the barrel 100, rotation of the lateral arm 144 is prevented due its engagement in the hook portion of the hook retaning member 157. The hook retaining member 157 is another means, besides the flexible string 146 and the longitudinal slot 116, for preventing rotation of the lateral arm 144 while rotating the plunger 102. In yet another alternative embodiment, a collar 161 is used in conjunction with an elongated longitudinal slot 116a in the barrel 100 to detach the engagement between the needle holder 108 and the barrel nozzle 110 and to prevent the lateral arm 144 from rotating with the plunger 102 during needle retraction (FIGS. 9a and 9b). The collar 161 is slidably mounted on the barrel 100 and includes an oblique slot 163 sloping in the opposite direction of the oblique slot 114 in the barrel 100. During normal use of the needle-syringe assembly, the lateral arm 144 protrudes through both the distal portion of the oblique slot 114 and the proximal portion of the oblique slot 163. To disengage the distal cylindrical portion 133 of the needle holder 108 from the barrel nozzle 110, the collar 161 is pulled toward the proximal end of the barrel 100. Such proximal movement of the collar 161 creates a "scissors-type" action which cams the lateral arm 144 proximally through the oblique slot 114 and distally through the oblique slot 163. After the lateral arm 144 reaches the proximal end of the oblique slot 114, the plunger 102 is rotated relative to the barrel 100 to continue needle retraction. While rotating the plunger 102, rotary movement of the lateral arm 144 relative to the barrel 100 is prevented by the elongated longitudinal slot 116a. The longitudinal slot 116a is of sufficient length to retain the lateral arm 144 as the lateral arm 144 moves through the entire helical slot 140 in the plunger 102. As the manufacture of the needle-syringe assembly is fairly conventional, it will not be described herein in detail. It suffices to say that the needle holder 108 is preferably manufactured using injection molding of a high impact thermoplastic such as polypropeline or ABS, and the needle 106 is injection molded within the needle holder 108. The remaining components of the assembly, including the barrel 100, the plunger 102, and the cap 104, are manufactured using conventional techniques. It can be seen from the foregoing description that the needle-syringe assembly performs all the conventional functions of injection syringes and yet, upon completion of injection, the hypodermic needle 106 is concealed within the barrel 100. The needle-syringe assembly can receive and inject medications any number of times into a particular patient by reciprocal longitudinal movement of the plunger 102 within the barrel 100. An unexpected advantage of the needle-syringe assembly is that its design prevents the plunger 102 from slipping out of the barrel 100 during normal use of the assembly. In some prior art designs, it is possible for the plunger to slip out of the barrel while withdrawing fluid from an injection vial, thereby spilling the medication out of the barrel. Not only does this waste medicine, but also the wasted medication might harm the administering physician or nurse. Additionally, the needle-syringe assembly is easy to manufacture, cost-effective, and easy to use in the field. The cost-effectiveness of the assembly is reflected in the benefits provided by the assembly to the patient in general and the society in particular. The assembly is compact because the needle holder 108 is retracted directly into the plunger 102 itself. Because the needle holder 108 retracts into the plunger 102, the plunger 102 need not be fully extended for needle retraction to occur. Thus, when discarded following use, the needle-syringe assembly contributes minimally to the bulk of refuse. Since retraction of the needle 106 and the needle holder 108 are actuated at the base plate 126 of the plunger 102, the hand of a user does not come into the vicinity of the needle point, thereby minimizing the possibility of a needle prick during retraction. Moreover, the assembly employs substantially the same number of components as conventional syringes, and does not require additional guards, sheaths, sleeves, springs, etc. to conceal the needle 106 following use. Referring next to FIGS. 13-17, the present invention further provides a guidewire insertion assembly. Since the construction of the guidewire insertion assembly is similar to the construction of the needle-syringe assembly, the guidewire insertion assembly will not be described herein in detail. It suffices to say that the guidewire insertion assembly has the same advantages as the needle-syringe assembly and is constructed from parts which are analogous to the parts of the needle-syringe assembly. These analogous parts are labelled in FIGS. 13-17 with reference numerals that vary from the reference numerals associated with the needle-syringe assembly by only the first digit. Thus, like the needle-syringe assembly, the guidewire insertion assembly includes a barrel 200 with a nozzle 210, a plunger 202 with a plunger cap 204, and a needle holder 208 with a hypodermic needle 206 connected thereto. The differences between the guidewire insertion assembly and the needle-syringe assembly are discussed below. First, in order to accommodate a guidewire 250, the leg portion 242 of the needle holder 208 is hollow from one end to the other (FIG. 13). Also, the base plate 226 of the plunger 202 is provided with a central aperture which opens into the coaxial cavity 234 of the plunger 202. This allows the guidewire 250 to be inserted into the plunger cavity 234 via the central aperture in the base plate 226, and to be fed through the plunger cavity 234, through the hollow leg portion 242 of the needle holder 208, and through the needle 206 (FIG. 16). Second, the leg portion 242 of the needle holder 208 includes an expanded portion 254 having a conventional one-way slit valve 256 which permits the guidewire 250 to be passed through the valve 256 towards the hypodermic needle 206 (FIG. 13). At the same time, the valve 256 prevents any flash back of blood or entry of air through the valve 256 during insertion of the guidewire 250 into the vein of a patient. Moreover, the valve 256 prevents air from leaking into the vein. The proximal portion of the coaxial cavity 234 of the plunge: 202 is widened to accommodate the expanded portion 254 of the needle holder 208. Third, during normal use, the guidewire insertion assembly includes a tubular plastic sleeve 258 inserted into the coaxial cavity 234 in the plunger 202. The sleeve 258 has flanges 260 designed to fit flush with the base plate 226 of the plunger 202. The sleeve 258 contains a tapering channel 262 for accepting and feeding the guidewire 250 into the valve 256 within the expanded needle holder portion 254. The sleeve 258 straightens the guidewire 250 and permits it to pass through the valve 256, through the needle holder 208 and needle 206, and into the vein of a patient. Fourth, to improve performance, the dimensions of some of the parts of the guidewire insertion assembly are different from the dimensions of the analogous parts of the needle-syringe assembly (FIGS. 13-14). In particular, the needle holder 208 is shorter and the hypodermic needle 206 is shorter than the analogous needle holder 108 and needle 106 of the needle-syringe assembly. Furthermore, the longitudinal slot 238 is shorter and the helical slot 240 is longer than the longitudinal and helical slots 138, 140 of the needle-syringe assembly in order to retract the longer needle 206. Also, the barrel 200 and retainer slot 216 of the guidewire insertion assembly are longer than the associated barrel 100 and the travel slot 116 of the needle-syringe assembly. To operate the guidewire insertion assembly, the protective cap of the hypodermic needle 206 is removed, the syringe is primed with normal saline, and the insertion site on the body of a patient is determined. Next, the skin at the insertion site is cleaned with an antiseptic solution and the needle tip is inserted into the vein of the patient (FIG. 15). The location of the needle tip in the vein is confirmed by aspirating a small amount of blood into the barrel 200. After returning the aspirated blood to the vein, the guidewire 250 is inserted in the plastic sleeve 258, passed through the valve 256 and the needle holder 208, and pushed until the guidewire 250 passes through the needle 206 and into the vein (FIG. 16). The insertion of the guidewire 250 into the vein using the guidewire insertion assembly is a relatively bleed free procedure. Following guidewire insertion, the needle 206 is withdrawn from the vein and the guidewire insertion assembly is slid backward over the guidewire 250. Next, the C-clamp 247 is rotated relative to the barrel 200 to permit disengagement of the taper lock at the nozzle 210 and proximal movement of the lateral arm 244 through the oblique slot 214 in response to counterclockwise rotation of the plunger 226. The base plate 226 of the plunger 202 is further rotated counterclockwise until the lateral arm 244 of the needle holder 208 reaches the proximal end of the helical slot 240. As the needle holder 208 ascends the plunger cavity 234, the expanded portion 254 of the needle holder 208 pushes the sleeve 258 proximally so as to eject the sleeve 258 from the plunger cavity 234 (FIG. 17). The lateral arm 244 of the needle holder 208 is locked in the detente 248 at the proximal end of the helical slot 240. As in the needle-syringe assembly, the barrel 200 and the plunger 202 are interlocked by a flexible string to prevent their separation from one another. With the needle 206 retracted inside the barrel 200 and the plunger 202, the guidewire insertion assembly is discarded in its entirety.

Claims: A needle-syringe assembly operable in a normal mode and convertible to a retraction mode, comprising: an elongated, generally cylindrical barrel (100,200) forming a single cylindrical interior cavity, a hollow nozzle (110,210) located at the distal end (120) of said barrel (100,200) and opening into the interior of said barrel (100, 200); a plunger (102,202) slidably mounted in said single cylindrical interior cavity of said barrel (100,200) and forming a longitudinal cavity extending between the distal end (120) and the proximal end of said plunger (102, 202); a needle holder (108,208) carrying a hollow needle (106,206) on the distal end thereof, said needle holder (108,208) being slidably mounted in said longitudinal cavity of said plunger (102, 202), said needle holder (108,208) detachably engaging said barrel (100,200) with the distal portion of said needle holder (108,208) disposed within said nozzle (110,210) of said barrel (100,200) during the normal mode; characterized in that said assembly further comprises a coupling mechanism which causes disengagement of said needle holder (108, 208) from said barrel (100, 200) to switch the assembly from the normal mode to the retraction mode and which in response to the rotation of the plunger relative to the barrel causes retraction of said needle holder (108, 208) into said longitudinal cavity of said plunger (102, 202) such that said needle (106, 206) is concealed within the assembly. The needle-syringe assembly of claim 1, wherein said retraction means includes retainer means for limiting rotation of said needle holder relative to said barrel (100,200) in response to rotation of said plunger (102,202) relative to said barrel. The needle-syringe assembly of claim 1, wherein said plunger (102,202) includes a longitudinal slot (138,238) exposing said cavity (134,234) to the outer surface of said plunger (102,202), and said needle holder (108,208) includes a leg portion (142,242) and a lateral arm, (144,244), said leg portion (142,242) being disposed within said cavity (134,234) and being longitudinally moveable through said cavity (134,234) in response to longitudinal movement of said plunger (102,202) during the normal mode, said lateral arm (144,244) extending laterally through said longitudinal slot (138,238) and being movable through said longitudinal slot (138,238) in response to longitudinal movement of said plunger (102,202) during the normal mode. A guidewire insertion assembly including the needle-syringe assembly of one of claims 1 to 3 comprising: a one-way valve (256) disposed within said needle holder for permitting a guidewire (250) to pass therethrough in one direction and for preventing blood from passing therethrough in the opposite direction.

Inventors: MAHURKAR SAKHARAM DHUNDIRAJ, MAHURKAR, SAKHARAM DHUNDIRAJ
Applicants: MAHURKAR SAKHARAM DHUNDIRAJ, MAHURKAR, SAKHARAM DHUNDIRAJ
Application year: 1994
Main classification: A61M5
IPC codes: A61M5, A61B5